Method and apparatus for the cementing of articles



Feb. 29, 1944. E 1 CRANDELL 2,342,846

METHOD AND APPARATUS FOR THE CEMENTING OF AR'fiQLES Filed May 1, 1941 I aware/$02 $2 0282 L. armada,

439 627W J. Gian;

fli i oz zzeg Patented Feb. 29, 1944 METHOD AND APPARATUS FOR THE CEMENTING OF ARTICLES Erwin L. Crandell, Wellesley, Mass., assignor to Compo Shoe Machinery Corporation, Boston, Mass., a corporation of Delaware Application May 1, 1941, Serial No. 391,293

'1 Claims.

This invention relates to the cementing together of adjacent parts of an article or manufacture through the application of heat derived from a high frequency electrostatic field, and relates more particularly to methods and apparatus utilizing high frequency electrostatic energy for cementing shoe parts together.

The Pi man Patent No. 2,087,480 and the Smith Patent 0. 2,109,323 disclose the cementing of shoe bodies to outsoles through the use of heat derived from high frequency electrostatic fields. Both of said patents disclose opposed electrodes connected to opposite sides of a high frequency electrical source for generating heat in heat responsive adhesives. Such electrode arrangements are well suited for supplying the desired heat, but there are disadvantages resulting from having to provide electric connections to metal last bottoms or to equivalent electrodes in a shoe assembly, such disadvantages requiring time and care which may slow down a conveyor system.

It has also been proposed to use interlaced electrodes such as disclosed in the Stevens and Dallas Patent No. 2,219,497, all arranged on one side of the work, but the eletrostatic fields so produced are so weak that too long periods of time are necessary for proper heating with the result that such electrode arrangements are unsuitable for quantity production.

This invention provides a multiple electrode arrangement which utilizes a pair of source electrodes which may be interlaced electrodes of the type disclosed in said Stevens and Dallas patent arranged at one side of the work and connected to the opposite sides of the high frequency oscillator, and utilizing one or more free electrodes arranged on the other side of the work and capacitively coupled to the source electrodes. Direct electrostatic fields are produced between the source electrodes and the capacitively coupled electrodes. This electrode arrangement provides the desired heat intensity in but a small fraction of the time required when utilizing the interlaced electrodes alone, and at the same time reduces the time and care required for high quality mass production.

An object of the invention is to decrease the time required for the cementing of parts of an article together through heat derived from an electrostatic field.

Another object of the invention is to improve the quality of articles having parts cemented to gether through heat derived from an electrostatic field.

The invention will now be described with reference to the drawing, of which:

Fig. 1 is a side elevation of a shoe press equipped with heating electrodes embodying this invention;

Fig. 2 is a circuit schematically illustrating the relations of the electrodes of Fig. 1 to each other and to a high frequency oscillator, and

Fig. 3 is a plan view with a portion broken away, of the heating electrodes of Fig. l.

The shoe press I0 of Fig. 1 includes the inflatable pad lI into which a fluid may be introduced and discharged to apply pressure to a shoe assembly I2, as disclosed in detail in said Smith patent.

In sole cementing, it is the practice to roughen the bottom of the lasted shoe and the top of the outsole and to coat these parts with an adhesive such as is disclosed in said Pitman patent.

The electrode element indicated generally by I3 includes the interlaced source electrodes I4 and I5 which may be enclosed between flexible leather sheets I6 and II, the margins of which may be joined by means of cement or stitches.

The electrodes I4 are interconnected by a common flexible conductor I8 and the electrodes I5 are interconnectedby'a common conductor I9, these conductors being arranged as shown by Fig. l to be connected through the insulators 20 and 2| respectively which are supported from the press III, to the terminals 22 and 23 respectively for connection to the opposite sides of an oscillator circuit as will be described.

With reference now to Fig. 2, the electrodes I4 are connected through the conductor I8, to the ground side of the oscillator tank coil 24 and the electrodes I5 are connected through the conductor I9 to the adjustable tap 25 at the live side of the coil.

The oscillator circuit is conventional, the live side of the coil 24 being connected through the blocking condenser 26 to the anode 21 of the vacuum tube triode 28 with high voltage direct current being supplied from any suitable source (not shown) and through the radio frequency choke 29 to the anode. The cathode 30 of the tube is connected to ground at 3| and to the ground side of the tank coil 24. A radio frequency of for example, 20 megacycles may be provided.

The electrode 32 is coupled electrically to the electrodes I4 and I5 by the capacity coupling formed by the dielectric between the adjacent surfaces of the electrodes I4 and I5, and of the electrade 32, the electrodes acting as plate of a condenser.

In shoe cementing, for example, the dielectric between the electrodes l4 and I5, and the electrode 32 consists of, when leather shoes are being cemented, the adjacent leather parts and the adhesive between the adjacent parts.

The capacity coupled electrode 32 may be a metal bottom 33 on the last 34 or it may be an electrode incorporated in the body of a shoe as disclosed in my copending application, Serial No. 387,823.

The source electrodes Hi and I5 and the capacity coupled electrode 32 are preferably so 'arranged with respect to spacing and surface areas that the capacity between the electrodes l4 and I5 is less than the capacity between the electrode 32, and the electrodes i4 and I5. With the electrodes so arranged, the electric field between the electrode 32 and the electrodes M and i5 is an intense direct field, stronger than the field between adjacent electrodes and i5, with the result that the field is concentrated where needed, in the work area.

The voltage provided by the oscillator should be insufficient to cause arcs between the elec trodes.

Using this electrode arrangement an intense, direct electrostatic field is produced, substantially as strong as that produced utilizing pairs of dianother side or said surface, all of said electrodes having such surface areas and being so spaced that the capacity between the electrodes of said plurality is less than the capacity between the electrodes of said plurality and said free electrode, and applying energy from a high frequency electric source to the electrodes of said plurality for producing a direct electrostatic field between said free electrode and said plurality of electrodes which is stronger than the stray field between the electrodes of said plurality.

2. The method in electrostatic heating which comprises placing a plurality of spaced electrodes on one side of a work surface; placing a free electrode having a length not substantially less than the overall length of said electrodes, overlying all of the electrodes of said plurality, on the opposite side of said surface, all of said electrodes having such surface areas and being so spaced that the capacity between the electrodes of said plurality is less than the capacity between the rectly connected electrodes on opposite sides of the work, as disclosed in said Pitman and Smith patents. Since this strong field is obtained without the necessity of establishing direct electrical contacts to the electrode 32 as previously required in the arrangements utilizing opposed electrodes on both sides of the work, this invention is particularly suitable for quantity production as where continuously moving conveyor systems are used.

As disclosed in said Smith patent, the pad H may be inflated for pressing the shoe parts to be cemented together, the pressure being maintained during timed heating cycles.

The time required in a heating cycle. utilizing the capacitively coupled electrode with the opposed electrodes according to this invention has been found to be less than half that required when the capacity coupled electrode is omitted and the electrode arrangement of said Stevens and Dallas patent is used.

Where adhesive is referred to in this specification and in the appended claims, an adhesive such as disclosed in said Pitman patent, and in which heat is generated by its inclusion in an alternating electrostatic field, is meant.

While the invention has been described in connection with the cementing of shoes, it is believed to be apparent that it may b used in the manufacture of other articles.

While one embodiment of the invention has been described for the purpose of illustration, it should be understood that the invention is not limited to the exact apparatus and combination and arrangement of apparatus illustrated as modifications thereof may be suggested by those skilled in the art without departure from the essence of the invention.

electrodes of said plurality and said free electrode, and applying energy from a high frequency electric source to the electrodes of said plurality for producing a direct electrostatic field between said free electrode and said plurality of electrodes which is stronger than the stray field between the electrodes of said plurality.

3. The method of cementing outsoles to shoe bodies which comprise placing an adhesive between an outsole and a shoe body; pressing the outsole and the shoe body together; placing a plurality of spaced electrodes along the bottom of the outsole extending the entire length thereof; placing a free electrode having a length not substantially less than the overall length of said electrodes and extending the entire length of aid outsole, within said shoe body overlying all of said electrodes, all of said electrodes having such surface areas and being so spaced that the capacity between the electrodes of said plurality is less than the capacity between the electrodes of said plurality and said free electrode, and applying energy from a high frequency electric source to the electrodes of said plurality for producing a direct electrostatic field between said plurality of electrodes and said free electrode which is stronger than the stray field between the electrode of said plurality.

4. Apparatus for cementing parts of a work articl with a heat responsive adhesive, comprising means for pressing said parts together from opposite sides with said adhesive therebetween; a plurality of spaced electrode for placement on one side of said pressed together parts; a free electrode overlying all of said electrodes for placement on another side of said pressed together parts, said free electrode having a length not substantially less than the overall length of the electrodes of said plurality; all of said electrodes having such surface areas and being so spaced that the capacity between the electrodes of said plurality is less than the capacity between the electrodes of said plurality and said free electrode; a high frequency electric source, and means for connecting the opposite sides of the output circuit of said source to the electrodes of said plurality for establishin a direct electrostatic field between said free electrode and said plurality of electrodes which is stronger than the tray field between the electrodes of said plurality.

5. Apparatus for cementing partsof a work article with a heat responsive adhesive, comprising means for pressing said parts together from opposite sides with said adhesive therebetween; a

plurality of spaced electrodes arranged alongside each other and having substantially flat work effectingsuriaces for placement on one side of said pressed together parts; a free electrode overlying all said electrodes for placement on the opposite side of said pressed together parts, said tree electrode extending substantially parallel to said surfaces and having a length not substantially less than the overall length of the electrodes of said plurality; all of said electrodes having such surface areas and being so spaced that the capacity between the electrodes of said plurality is less than the capacity between the electrodes oi. said plurality and said free electrode"; a high frequency electric source, and means for connecting the opposite sides of the output circuit of said source to the electrodes of said plurality for establishing a direct electrostatic field between said free electrode and said plurality of electrodes which is stronger than the stray field between the electrodes of said plurality.

6. Apparatus for cementin parts of a work article with a heat responsive adhesive, comprising means for pressing said parts together from opposite sides with said adhesive therebetween;

a pluralit of interlaced, spaced electrodes for placement on one side of said pressed together parts; a pair of electrical conductors connecting alternate of said electrodes together; a free electrode overlying all of said electrodes for placement on another side of said pressed together parts, said free electrode having a length not substantially less than the overall length of said interlaced electrodes; all of said electrodes having such surface areas and being so spaced that the capacity between the electrodes of said plurality is less than the capacity between the electrodes of said plurality and said tree electrodes; 9. high frequency electric source, and means connecting opposite sides of the output of said source to said conductors for establishing a direct electrostatic field between said tree electrode and said interlaced electrodes which is stronger than the stray field between the electrodes of said plurality.

'7. Apparatus for cementing parts or a work article with a heat responsive adhesive, comprising means for pressing said parts together from opposite sides with said adhesive therebetween; a plurality of interlaced, spaced lectrodes arranged alongside each other and having substantially flat work effecting surfaces for placement on one side of said pressed together parts: a pair of electrical conductors connecting alternate of said electrodes together; a free electrode overlying all of'said electrode for placement on the opposite side of said pressed together parts, said free electrode extending substantially parallel to said surfaces and having a length not substantially less than the overall length of said interlaced electrodes; all of said electrodes having such surface areas and being so spaced that the capacity between the electrodes of said plurality is less than the capacity between the electrodes of said plurality and said free electrode; a high frequency electric source, and means connecting opposite sides 01' the output of said source to said conductors for establishing a direct electrostatic field between said free electrode and said interlaced electrodes which is stronger than the stray field between the electrodes of said plurality.

ERVIN L. CRANDELL. 

